[gb]

It ain't over yet. Deep slab avalanches (down to the crust from mid-February) can release several days after a period of warming. During warm periods the upper layers of the snowpack are more or less plastic, as stress is redistributed through the pack, the weak layer can continue to fail. Or cornices can fall. The South Cascades warmed Thursday PM and have cooled slightly today. Precip continued until early this morning. The North Cascades only warmed to 5000-5500' (to freezing) thus far but that changes tonight and Monday with warming to 8000' with loading of new snow and then rain. The really big avalanches from higher elevation terrain will be increasingly likely. While the highest probability will be Monday-Tuesday for these slides, the risk will continue until at least Wednesday with the warm temperatures and continued stress redistribution. A glance at Roger's Pass shows that there have already been a few Class 4 avalanches that have run full path. The Cascades should have the same issue. The problem is regional from Oregon, likely east to SLC and Jackson and north and east to the Coast Range and Northern Rockies of BC. Watch exposure (low probability, certain consequences) to paths even in valley bottoms as the lower paths have enough snow cover from the cold winter.

[ale_capone]

[ale_capone]

I remember a similar cycle a few years ago. There was a few days of very large, unpredictable avalanches. The big path from the top of little plugs west face ran huge all the way down to surprise creek, up the other side, and down the creek a few hundred yards. Taking with it some big trees. Leaving huge debris piles in what one might think is safe... Similar events happened on nimbus, thunder, lichtenberg. Over these few days.. randomly, natural, deadly sized. I was communicating with nwac about the events at the time, and was reflected in the reports.

[ale_capone]

http://www.turns-all-year.com/skiing_snowboarding/trip_reports/index.php?topic=30614.0 It was during the same time of year, end of February, early March, 2014. There are some photos from the bottom of the path several posts down.

[gb]

[trestle]

I would love to see those pics, gb, if you ever have a chance scan or digitize them in some way.

[gb]

[Chief Joseph]

I plan to return to wwa Tuesday and am trying to decide whether to take Snoqualmie or Stevens pass. I typically take Stevens as there is less traffic and it's a more direct route to My place out past Granite falls. I really hate to take Snoqualmie and go through Seattle on a weekday as I typically arrive there around rush hour, so then I usually go north from north bend to monroe. The forecast calls for about 35 degrees on stevens and 43 on snoqualmie, in your opinion which route should be safer avalanche wise? With 35 degrees I would think ice should not be much of an issue, yet still very possible.

[moonspots]

[treeswarper]

[gb]

Meanwhile in Canada: High-High-High:

[gb]

The top part of the Cascade snowpack may still be unstable......the top 1". Crampons or ice skates with a temperature in the teens?

[Riverside Laker]

When did the yuuuuuge avalanche on Granite Mtn come down? It's one of the most impressive debris I've seen. Looked like a climax avalanche.

[zephyr]

[pipedream]

As I commented on the TR referenced by this thread, my guess is that slide (and several others) occurred during the avy cycle which began during the afternoon of Thurs. 3/9. I was skiing at Alpental that morning and not only was the snow increasingly reactive, but WSDOT shut WB 90 down by 11:30 due to what I'd heard was a natural release on Granite's south side which reached the highway. There was then a round of control work which produced massive-sounding results and noticeable debris cleared off the roadway when WB finally reopened after 3. I triggered a D1 storm slab, roughly 150' wide by 8-10" deep while cutting across a knoll in the lower back bowls (formerly "Alpental backcountry"). Elevator gate was open that morning and I think it should've been closed by the afternoon but with the insanity of highway closures and rapid loading + warming, they shut most of the mountain down at noon anyways.